Centerless grinding



Feb. 14, 1928. 1,659,220

c. 0. SMITH ET AL CENTERLES S GRINDING Filed April '28. 1926 2 SheetS-Sheet 1 Feb. 14-, 1928. 1,659,220

' C. O. SMlTH ET AL CENTERLES S GRINDING Filed April 28, 1926 2 Sheets5heet 2 Patented as 14,1928.

UNITED. STATES PATENT OFFICE.

CLAYTON O. SIITH, O1 WONOESTEB, MASSACHUSETTS, AND CLEMENT BOOTH, OI DAN- IBUBY OONNEUI'IOUT, ASSIGNORS, BY MESNE ASSIGNMENTS, TO CINCINNATI GBINDEBS INOOBPOBATED, OF CINCINNATI, OHIO, A CORPORATION 01 OHIO.

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' Application fled April as, 1925;. Serial No. 105,258.

This invention relates .toimprovements in the art and apparatus of centerless grinding and has particular reference to a novel and improved process and apparatus for the production of concentric surfaces.

'The further object of the invention is the provision of an attachment which will make it possible to produce in a centerless grinding machine a second surface in predetermined axial relation to a previously ground surface.

A further object'of the invention is the provision of a novel apparatuswhich will make it possible toquickly produce a taper shank for a drill or like member, in which the axis of the taper portion will coincide with the axis of the body of .the drill within very fine limits.

An additional object of the invention is the revision of an improved simple and readily operable work-holding mechanism for use in conjunction with a standard type opposed wheel centerless grinding machine,-

, which will satisfactorily locate and position the work for the grinding operation.

Further objects and advantages of the resent invention should be readily apparent y reference .to the following specification taken iii-connection with the accompanying drawings, may make any modification 1n specific details of construction shown and described within the sec of the appended claims, without departing from or exceeding the spirit of the invention. a Figure 1 reprwents a fragmentary side elevation of'a grinder embodying the invention.

Figure 2, represents a sectional view with parts in'elevation, taken as on the line 2-2 of Figure 1. V

, Figure 3, is a fragmentary sectional view on line 3-3 of Figure 2. and Figure 4 is a section on line 4 40f Figure 2.

In the drawings in which similar characters of reference are employed to denote corresponding parts throughout the several views the letter A designates the base or bed of a centerless grinding machine of well 60 known commercial type, having the slides B and C for the regulating wheel D and grinding wheel E respect vely. A bridging portion E extends transversely of the space between the lower portions of the grinding and it will be understood that we' and regulatin wheels and has a guide G for the reciproca le plunger member H controlled by pinion I and handle J. This plunger member is provided with cam portions as at K, for elevation of the posts L which bear the work support M. -As the foregbing parts are of standard commercial construction it is believed unnecessary to give them further description in this connection.

Prior to the present invention it has been customary in machines of this general t to place the work to be operated upon irectly on the work support or blade and in the throat between the grinding and regulatin wheels for joint engagement by said whee "s. This method of operation however,

.cannot be employed with entire satisfaction when it is essential that two surfaces of different shapes or diameters must be'formed concentric, one with the other, within the usual manufacturing limits.

On the other hand, it is desirable when a portion of the grinding of the article may be performed to maximum advantage by the use of'standard centerless grinder machines,

to be able to perform the balance of the work on the same machines to the end, that smaller shops for example, will not be .put to the expense of purchasing two difierent equipments for the-job; that on the contrary the different operations may all be per-- formed on the same machine b a mere 1nterchange'or truing of one of t e wheels of the machine, or if a battery of machines be owned, the several machines may be interchangeably employed aswork ,conditions may re mm. W

e particular type of work chosen for purpose of illustration of the utility of the present invention is that of adrill member intended to have the fluted drill portion N and the taper shank O, which for satisfactory operation must beconcentrically disposed as respects each other. The portion N may be ground by the thru-fe ed method 6n the standard centerless grinder and it is then necessary to produce the shank O of proper taper and proper concentricity. In the accomplishment of this result use is made of a work-holdi'n fixture, comprisin a tubular shank 10, having an outer cylin ricaLportion 11 and concentric therewith a taper socket 12 for the collet or chuck 13 and adapted to center the drill N within the portion 11 and to clamp same in place. This of hand-wheel 15 on the end of draw-rod 16, which extends through tubular portion 10 of the device.

In ordinary centerless grinding the work support is of nature to directly engage the work being operated upon, but in the present instance, use is made of a special support bar M, Having the bracket 17 in the form of a half-bearing to receive and steady the shank 10 of the work-holding fixture. Between the wheels the support is provided with a blade member 18, having an inclined upper face 19, for peripheral engagement with the cylindrical portion 11 of the fixture. To further aid in retaining the fixture in osition on the work support, the support is ormed with a second bracket 20 to which is pivotally secured a. rock-arm 21, bearing at its upper end the guide roller 22 and having in its lower end a socket 23 for the compression spring .24, which urges the low er end of the arm outwardly, thus tending to swing the roller forwardly toward the vertical plane of the work support. An adjusting screw 25 passing through the lower end of the arm and socket and engaged in the bracket 20, serves to limit the swinging movement of the arm as actuated by spring 24, as should be readily understood by reference to Figure 4.

It will be noted that the pivot support for arm 21 is in the form of a long spindle 26, having its outer end journaled in a second bracket 27 on the support, and having a handle 28 which may be depressed to rock the arm against the urge of its actuating spring.

In the use of the invention the grinding wheel operates downwardly toward the support at a high or grinding rate of speed,

while the regulating wheel moves upward-- ly at a very slow-rate to control the rate of rotation of the work. However, as distinguished from ordinary centerless grinding practice the two wheels in place of being directly opposite to each other are disposed in a staggered or ofi-set relation as best shown in Figure 3 of the drawings." As a result of this relationship the cylindrical portion 11 of the work-holding fixture is brought to bear against the regulating wheel and is held over against the regulating wheel by spring actuated arm 21, whose roller 22 rides against the fixture, permitting its free rotation under the urge of the regulating wheel. As mentioned, the grinding wheel i laterally ofi-set, and is fed in to just engage the width of surface which it is desired to grind to form the taper shank O. The degree of taper is varied, either by angular adjustment of the grinding wheel or by forming its operative peripheral surface witha taper corresponding to that to be reproduce I Y as to remove the desired amount of stock from the shank O. In the commercial production of ground shanks, use is preferably made of several of the work-holding fixtures, so that certain fixtures may be loaded and un loaded, while one is in operative position in the machine. To introduce the fixture and its work piece without disturbing the setting of the machine, use is made of the lever J, which wheniiiov'e'd upwardly causes the cam surfaces K toraise the posts L and thus the work-support to a wider part of thegrinding throat formed by the adjacent portions of the grinding and regulating wheels. In this position handle 28 is depressed to swing roller 22 outwardly, and the work fixture placed in the machine resting on face 19,0f plate 18, and on the bearing yoke 17. Downward rocking of handle J then causes reverse movement of the worksupport M and associate parts, into a narrower art of the grinding throat, this movement eing assisted by action of springs P. This downward movement will cause the regulating wheel to more tightly engage the cylindrical portion 11 of the fixture, and at the same time will bring the shank of the work piece in operative engagement with the grinding wheel for the desired stock removal and finish. After the grinding has been completed, the Work-support is again raised, the work-holding fixture withdrawn and a new one with fresh work-piece inserted. In this manner the various work-pieces may be satisfactorily ground without any adjustments of the machine, other than the raising and lowering of the work-support or an occasional variance in the throat or distance between the wheels, due to the wear of grinding.

Inasmuch as the position of the fixture is absolutely determined by the engagement of the regulatin wheel therewith, and since the work-hol ing collet is central with respeet to this portion 11, it follows that the work-portions N will be accurately centeredwithin the fixture and will be given a rotary motion about the axis of the portion N. Consequently, the member O-forming a continuation of the portion N, will likewise r0 tate about the axis of N and when so rotated and brought into contact with the grinding wheel, the grinding wheel-will remove all surplus stock and .produce a tapered surface of revolution, whose axis is a continuation of that of the body 'of the work. As a result the two parts of the drill, that is the body and shank will be accurately concentrically formed and it is possible for the first time to produce an article of this type with con-- i for every piece to lie-operated upon. The

position of the body of the work-piece and its rotation will therefore be determined and controlled by the regulating wheel in a new, novel and eificient manner.

We claim 1. In combination 3 with a centerless grinder embodying opposed grinding and regulating wheels and an intermediate worksupport, a work-holding fixture having a cylindrical portion for co-operation with the work-support and regulating wheel, and having a work-receiving socket concentric with the periphery thereof, and means on the work-support for urging the cylindrical portion of the work-holding fixture in the direction of the regulating wheel.

2. The combination with a centerless grinder, including a work-support, a grinding wheel on one side of the support and a regulating wheel on the other,of a fixture for insuring concentric grinding of a workpiece, said fixture having a central socket for receiving a portion vof the work-piece and a concentric outer cylindrical surface for'engagement with the regulating wheel,

- means on the support for steadying the work-holder and additional means for yieldingly urging the cylindrical portion of the work-holder in the direction of the regulating wheel. i

'3. A grinding machine of the character described, including a support, a workholder rotatably mounted upon the support,

a rotary wheel frictionally engaging the work-holder to control the rotation thereof, and a grinding wheel olf-set as respects the work-holder to operate on a work-piece.

when projecting from the work-holder.

4. A centerless grinding machine including a grinding wheel and a regulating wheel operated at a slow rate of rotation for controlling the surface speed of work during action of the grinding wheel thereon, said wheels being disposed in opposed but stagered relation, a-work-support intermediate the wheels, a work-holding fixture and means on the support for holding the fixture out of 'line' with the y and in engagement with the oil-set or staggered portion of the regulating wheel.

The combination with a centerless grinding machine, including a grinding wheel, a regulating wheel and an intermediate work-support, of a work-holding fixture, means on the support for holding the work-receiving end of the fixture in en-' gagement with the regulating wheel and adjacent' the grinding wheel, whereby the grinding wheel lating wheel operated at a slow rate of speed to control the rotation of the work, said wheels being disposed in staggered relation, whereby the regulating wheel may engage a work holding fixture while the grinding wheel engages Work in said fixture, and an intermediate work-support, said support having a portion forming a rest, a workfixture having a cylindrical surface for engagement with the rest and having a socket concentric with said cylindrical surface, and

means on the support for engagement with the cylindrical surface at a point opposite the regulating wheel for urging said cylindrical surface into engagement withthe regulating wheel.

71. In combination with a centerless' grinder, including a grinding wheel, a regulating wheel disposed in staggered or laterally ofiset relation to the grinding wheel and an intermediate work-support, said support having a portion forming a rest, a work-fixture having a cylindrical surface-for engagement with the rest and having a socket 100. concentric with said cylindrical surface, means on the support for engagement with the cylindrical surface at a o1nt opposite the regulating wheel for urging said cylmdrical surface into engagement with the 5 regulating wheel, and additional means on the support at a point remote from the regulating wheel for controlling the axial ahnement of the fixture on the support.

8. In combination with a centerless er, including a grinding wheel, a regu atmg wheel and an intermediate worksupport, said support having a portion formmg a rest, a work-fixture having a cylindrical surface for engagement with the rest and having a L support at a point remote from the regulating wheel for controlling the axial almement of the fixture on the supportyand means for clamping a work-piece in position within the socket of thecfixtu're.

9. In combination with a centerles's rinder, including a grinding wheel, a regu atmg wheel and an intermediate work-support,

said support having a portion forming a rest,

rind- I no with the cylindrical surface at apoint 0 po-- site the regulating wh'eel for'urgmg sai .cy-

lindrical surface into engagement with. the regulating wheel, additional means 'on the support at a point remote from the regulating wheel for" controlling the axial alinement of the fixture on the support, means for clamping a work-piece in position within the socket of the fixture and means for vertically shifting the support and fixture to vary the engagement of the fixture with the regulating wheel and of a work-piece carried by the fixture with the grinding wheel.

10. In a centerless grinder the combination with the grinding and regulating wheels and an intermediate work-support, of a fix-' ture engaging yoke carried by the work-support, brackets additionally secured on the work support, a spindle pivoted in said brackets, rock arm secured on the spindle andprovided with a. roller contact, means for automatically urging the rock arm in one direction and additional means for manually shifting the rock arm in-the opposite direc tion. J

11. In a centerless grinder including a rinding wheel, a regulating wheel and: an intermediate work-support, means for urging a device on the support in the direction of the regulating wheel, said means comprising 'a rock arm pivoted to the support, a contact member carried by the rock arm, means for resiliently urging the arm and contact member transversely of the support in the direction of the regulating wheel and adjustable means for limiting the inward movement of the contact.

12. In a centerless grinder including a drical surface,-a draw-in collet of taper form intermediate work-support, means for urging a device on the support in the direction of the regulatin wheel, said means comprising a rock arm pivoted to the support, a. contact member carried by the rock arm, means'for resilientlyurging the arm and contact member transversely of the support in the direction of the regulating wheel, adjustable means for limiting the inward movement of the contact and additional means for shifting the contact in a reverse direction.

13. A work-holding fixture for use in a centerless grinder, comprising a hollow shank having a cylindrical head at one end thereof, said headbe'ing formed with a tapered socket concentric with the outer cylindrical surface, a draw-in collet of taper form disposed within the socket and having a work-receiving socket concentric with the outer cylindrical surface, a draw-rod extending through the tubular shank, and means for engaging the-shank and draw-rod for moving the collet within its socket.

.In witness whereof, we hereunto subscribe our names.

CLAYTON 0. SMITH. CLEMENT BOOTH. 

